I've had a look at the map and came to the conclusion that trying to figure it out on your own may be impossible. If you want to try anyway, skip the remainder of this post.

The "coolant chambers" are the the two rooms with the long spinning pipe at the lowest level of the map. Don't actually walk into the pipe, but jump into the water below. Those water tanks seem to be sealed off, but they actually have one invisible hole, each.The first one to go to is the western coolant chamber. (It's the one you end up in when teleporting back from the "hint room".) Underwater in in the wall under the southern entry is a hole that is one-way see-though (it appears solid from within the coolant chamber) that leads to a switch. Use it (as if you want to get into a vehicle) to open a secret door in the other coolant chamber. Now quickly make your way to the other (eastern) chamber, as the door only stays open for about 72 real time seconds. (You will probably have to suicide or coordinate this in your team.) The secret door is in the floor of the eastern coolant chamber water tank, at its east wall.Dive down until you can walk again. You will find yourself in a strange-looking corridor with several alcoves left and right. Go to the end of the corridor and turn right. Inside that last alcove, stay at the right-hand side wall and crouch (!) to the rear right corner. From there go to the alcove's rear left corner, always staying at the rear wall. If you don't follow these instructions, you are likely to walk into one of the invisible death traps. If you managed to reach the rear left corner of the rear right alcove, you will hit a teleporter that brings you to an invisible rotating platform above the central node.The platform consists of two parts that spin in opposite directions. The end of each part is indicated by a flare that rotates with the platform part. To makes things more confusing, the platform may decide to spin wildly for a second when you land on it. Let it come to its slow rotating rest first, then carefully walk towards the first flare. Look around to see if you can find the flare of the other platform, wait until it almost matches your platform's orientation, then jump towards it. Again, the platform part may decide to spin wildly for a second, so just let it calm down. Walk towards the second flare and wait for a good moment to jump over to the manta. Don't worry about people seeing you while you are on the platforms, they can't shoot through the platforms so you should be relatively safe up there.Final note: both mantas are accessible through the same way, so if you decide to open the route to the Manta, your team better be quick. If the enemy notice, they may decide to go straight to the second coolant chamber and through the secret door you generously opened for them as well.

Ouff, I barely managed to find that strange room, but I got killed by an invisible trap. Who came up with this? xDGotta try this some day when I have more time. Thanks for the info, Wormby! Wouldn't have figured this all out on my own.

SlipStreamer (or SlipStreams_65) of the now defunct Titans UT community was the mastermind behind this goosechase, that's who .

Anyway, I was considering posting the same lengthy writeup, but was kinda bored to slog through it, so now that the Worm has taken care of that, I can just settle for offering more bite-sized, practical tips to anyone hoping to get the hang of this in offline play. Which is basically code for cheats!

- These commands aren't enabled during online play (for reasons that will become all too obvious), but when you're the master of your own offline game, you can use the different rendering console commands to your advantage. Specifically, since you're looking for unnoticeable areas in both pools, you can pull down the console and type rmode 1 to switch to wireframe view and quickly locate where the hidden (western) control room and the (eastern) vertical tunnel are. Since rmode isn't a toggleable command (its syntax is "rmode X" where X goes from 1 to 15 I think), to return to normal, dynamically lit rendering mode you'll need to type rmode 5; also of use for finding stuff hidden in absolute darkness is the "textured", i.e. everything fully lit, view which you get with rmode 6. The most convenient way to access those is by keybinding 'em to 3 adjacent keys for all kinds of map testing purposes; for me that's the comma, period and slash keys for wireframe, normal and unshadowed mode respectively. That takes care of the underwater locating part.

- When navigating the kill volumes maze, there's one other console command you can use to understand exactly how the volumes have been placed: the toggleable show volumes command.

As mentioned before, those won't work online, so make sure you memorize the whole thing as best as you can. What's probably far worse for the ultimate goal of anyone trying all this, however, is that these 2 invisible movers Wormbo mentioned that rotate at the top of the central area have repeatedly been reported to be moving pretty erratically in online games (likely caused by the server's chosen tickrate) to an extent where it becomes pointless to go through the whole ordeal just so you can plummet down below almost as soon as you can see the manta within reach in the distance. Much like all of you now, I tried getting that manta a number of times years ago on some servers, even during off hours when I'd be all alone, and the first mover would still manage to kick me off it even as I was just standing there. So, all in all, yeah, you're better off trying what Cheese_it proposed in the previous page, i.e. to shield jump your way on top of your enemy's core door adjacent arch and fire some shit at your manta (rockets, shock shots, etc.) till that sucker drops. At least that method's known to (eventually) work .

Moving pictures tell more than a thousand (or at least a few hundred) words:[video]http://www.youtube.com/watch?v=Q-JP6U-HpYw[/video]Originally I wanted to do it without suiciding, but after accidentally dropping into the water again time I went for the respawn anyway.